Subtract 18/70 from 81/72, Solve 1 9/72

Subtract 18/70 from 81/72

1^st number: 1 9/72, 2^nd number: 18/70

81/72 - 18/70 is 243/280.

Find the least common denominator or LCM of the two denominators:
LCM of 72 and 70 is 2520

Next, find the equivalent fraction of both fractional numbers with denominator 2520
For the 1st fraction, since 72 × 35 = 2520,
81/72 = 81 × 35/72 × 35 = 2835/2520
Likewise, for the 2nd fraction, since 70 × 36 = 2520,
18/70 = 18 × 36/70 × 36 = 648/2520
Subtract the two like fractions:
2835/2520 - 648/2520 = 2835 - 648/2520 = 2187/2520
After reducing the fraction, the answer is 243/280

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